Hookup resend verification email links

* Add reset password resend to the fxa-client wrapper.
* Rename requestPasswordReset to passwordReset - update consumers.
* Add visual feedback when email is resent.
* Add BaseView.preventDefaultThen to reduce event handling boilerplate. BaseView.preventDefault returns a proxy event handler that backbone can use to call event.preventDefault, then another handler.

fixes #272
fix merge bug